As known, many pourable products are sold in a wide range of bottles or containers, which are sterilized, filled and closed in container handling plants typically including a plurality of processing stations or machines, such as rinsing machines, filling machines, capping machines and labelling machines.
These processing stations can be defined by linear machines or, more frequently, by carousel-type machines. The following description will refer to carousel-type machines only, although this is in no way intended to limit the scope of protection of the present application.
The containers to be handled are generally fed to and removed from these machines by means of a transport system including star wheels and linear conveyors.
Known container handling plants are therefore fairly bulky and allow little freedom of choice in terms of layout; moreover, this kind of plants requires quite complicated adjustments to synchronize the different processing stations and entails relatively high operating and maintenance costs.
Another problem posed in respect of known filling machines is the formation of foam at the end of the operation of filling the container.
This problem is mainly caused by the fact that, for reasons of economy, commercial containers are not such larger than the volume required for accommodating of the contents. Thus, during filling operations, which have to be carried out at high speed, it is common for some amount of liquid in the form of foam to bubble over the top of the container prior to the container being capped or sealed. The product loss can be as high as ten percent, which translates into higher cost for the consumer or lower profitability for the bottler, or both.
To reduce this product loss, some filling machines include a dwell station that allows for the product foam in a recently filled container to settle prior to capping.
Other filling machines include a short suction pipe adapted to be introduced into the container to be sealed, and a suction system whereby the foam over the top surface of the liquid is removed and optionally recycled into the product reservoir.
Some filling machines may also use blast nozzles for blowing any drops and residual foam from the surfaces to be sealed or capped.
Some filling machines reduce the temperature of the liquid at the mixing tanks or other reservoirs to reduce foaming.
In certain cases, the containers are purposefully overfilled to compensate for lost product in the form of foam and thereby achieve the desired net fill volume, which results in undesirable product loss.
Other possible solutions are based on the use of ultrasonic waves for collapsing the foam; in practice, the portion of liquid forming the foam again becomes part of the liquid content of the container rather than being wasted.
In order to solve the two above-described problems (bulky container handling plants and formation of foam at the end of the filling operation), the applicant has recently proposed to perform both the filling and the labelling operation on the same carousel as well as to rotate the containers during filling (see EP-A-2749501).
The applicant has in fact observed that, by rotating each container about its axis while the same container is filled with the pourable product and is transported in a revolution motion by the carousel, it is possible to obtain the following effects:                the centrifugal force caused by this double rotation generates an additional pressure on the pourable product in the container, which entraps the carbon dioxide into the product; and        the pourable product comes down into the container along the lateral wall thereof instead of centrally.        
Both these effects permits to obtain a significant reduction in the formation of foam at the end of the filling operation.
Though satisfactory, the recently-proposed solution still leaves room for further improvements, especially as to achieve a further reduction of the formation of foam in the containers subjected to the filling operation, without using additional external tools.